1. Field of the Invention
This invention relates to a cassette loading device for moving up and down a cassette holder which accommodates a cassette and also to a recording and/or reproducing apparatus such as a VTR or the like which is equipped with the cassette loading device.
2. Description of the Related Art
Referring to FIG. 1 which is a side view of the conventional cassette loading device, a cassette 101 is inserted into a cassette holder 102. A pair of levers 103 and 104 form a link and are rotatably interconnected by a shaft 105. The lever 103 has one end thereof rotatably supported by a chassis 107 through a shaft 106 and the other end thereof slidably engaging a shaft 109 of the cassette holder 102 through a slot 108. The lever 104 has one end thereof slidably engaging a slot 111 of the chassis 107 through a shaft 110 and the other end thereof rotatably supported by the cassette holder 102 by shaft 112. An ascent urging spring 113 stretches between the levers 103 and 104 for urging an upward motion.
When the cassette holder 102 is pushed with the cassette 101 inserted into the cassette holder 102, the link action of the levers 103 and 104 causes the cassette holder 102 to descend. When the cassette holder 102 is unlocked in a descended position, the levers 103 and 104 are operated by the spring 113 to cause the cassette holder 102 to ascend.
In the conventional cassette loading device, a gear 103a is provided at the fore end of the lever 103 on the side of the shaft 106. The gear 103a is in mesh with a damper 115 which is disposed on the chassis 107. When the cassette holder 102 is moved upward by the force of the spring 113, the gear 103a of the lever 103 causes the damper 115 to rotate. The ascent of the cassette holder 102 is smoothed with a load imposed on the ascent by the rotation of the damper 115.
Since the damper 115 is disposed on the side of the shaft 106 which is the center of rotation of the lever 103, the distance between the center of rotation of the gear 103a of the lever 103 and that of the damper 115 is unvarying. Therefore, a torque applied from the damper 115 to the lever 103 remains the same throughout the motion of the cassette holder 102 from its descended position to its ascended position. The torque of the damper 115 is set on the basis of the spring pressure of the spring 113 which is charged when the cassette holder 102 is in its descended position. Therefore, the load on the damper 115 becomes too large in the neighborhood of the ascended position of the cassette holder 102 where the spring pressure becomes weaker.
Further, if the damper 115 is disposed near to the center of rotation of the gear 103a for the purpose of reducing the size of the device, the torque of the damper 115 would increase to necessitate an increase of the distance between the center of rotation of the damper 115 and that of the gear 103a. Therefore, the reduction in size has been difficult. Further, if the lever 103 is made of metal, the gear of the damper 115 might be cut by the gear 103a. To avoid this, it is necessary, for example, to arrange an intermediate gear, which then necessitates an increase in space.